The present invention relates to a small-sized printer. Recently, there is an increasing demand for small-sized and light weight printers, as a result of the current tendency of adoption of LSI circuit parts. In fact, also in the field of electronic desk-top calculators, there have been proposed various portable and handy desk-top calculators provided with printers. There are also many requirements to be fulfilled such as minimization of size and weight, decrease in power consumption, reduction of production costs, making possible operation by a battery drive and so forth.
Most of printers conventionally used in combination with desk-top calculators are of mechanical impact type which make use of printing types. This type of printer, however, requires a large number of parts, which is quite contrary to the requirement of reduced size and weight. Thus, the printer of mechanical impact type cannot fully meet the requisite of reduced size and weight which are essential in combination with a desk-top calculator. Rather, for this kind of purpose, printers of thermal type or electro-sensitive type can advantageously be used, because of their simplified constructions.
Various printing systems of the thermal and electro-sensitive types have been proposed and actually used. One of these systems is so-called a serial system employing a printing head having a plurality of printing elements arranged in a row extending in the direction of paper feeding. In this system, the printing is effected by shifting the printing head widthwise of the paper. In another system called parallel system, the printing elements are arrange in a row in the widthwise direction of the paper, and the printing is made by feeding the paper at a small rate. Further, in still another system referred to as serial-parallel system, printing elements are arranged in a row in the widthwise of the paper, at a space equal to an integral multiple of the width of one character. The printing is made by reciprocatingly shifting the printing elements, while feeding the paper.
Unfortunately, however, there has been proposed almost no printer which would fully meet the aforementioned requirements such as minimization of size and weight, decrease in power consumption, reduction of production costs and lower driving voltage of the power source, all of which are essential when the printer is used in combination with a desk-top calculator.